Evaluation of the response of the ESR-alanine signal to different LET irradiations

The use of charged particles in tumour treatment, known as hadrotherapy, provides simi- lar dose coverage to photon therapy while better sparing healthy tissues due to the finite range of particles, which is advantageous for complex-shaped tumours. However, charged particles have a higher linear energy transfer (LET) than photons, potentially causing satu- ration and/or recombination in certain radiation detectors, such as alanine dosimeters. This study investigates the quenching effects of charged particle irradiation on the electron spin resonance (ESR) signal of alanine and explores its spectrum shape as a LET discrimination factor. Alanine dosimeters were irradiated at San Matteo Hospital and Fondazione CNAO in Pavia, Italy, using proton and carbon ion beams. The ESR signal was measured and the ratio of satellite to central lines was analysed. Preliminary results showed variations in this ratio under different LET and microwave power conditions. This work was partially funded by the European Union - Next Generation EU through Projects SAMOTHRACEs (MUR, PNRR-M4C2, ECS 00000022) and Mission 4 Component 2 Inv. 1.5 CUP B83C22003930001.